We Claim:
1. A method (60) for detecting and preventing diesel particulate filter (26) failure
modes, comprising:
measuring a plurality of input signal parameters (32-46) from an exhaust gas of an internal combustion engine (12) using a plurality of sensors (14, 20, 24, 28) connected to an after treatment system (18);
calibrating a lookup table (47) based on concentration of the input signal parameters (32-46) at a plurality of operating condition of the engine (12) and/or rate of change of the input signal parameters (32-46) by an after treatment control unit
(16);
detecting abnormality of soot emission from the engine (12) based on deviation of the input signal parameters (32-46) from a predetermined reference value stored on the lookup table (47); and
de-rating performance of the engine (12) to prevent failure of the diesel particulate filter (26).
2. The method (60) as claimed in claim 1, wherein the step of measuring the input
signal parameters (32-46) from the exhaust gas, further comprises:
measuring an oxygen signal (32) corresponding to an oxygen level in the exhaust gas using an NOx sensor (14) placed upstream of the after treatment system (18); and updating the lookup table (47) based on the concentration of the oxygen level at the plurality of operating condition of the engine (12) to identify abnormality of the soot emission from the engine (12).
3. The method (60) as claimed in claim 1, wherein the step of measuring the input
signal parameters (32-46) from the exhaust gas, further comprises:
measuring an absolute value and/or rate of change of pressure drop (34) across the diesel particulate filter (26) during the soot accumulation using a delta pressure sensor (28); and

updating the lookup table (47) based on difference in pressure drop to identify abnormality of the soot emission from the engine (12).
4. The method (60) as claimed in claim 1, wherein the step of measuring the input
signal parameters (32-46) from the exhaust gas, further comprises:
measuring an input temperature (36) and difference in temperature (38) across the diesel oxidation catalyst (22) using a temperature sensor (20, 24); and
updating the lookup table (47) based on a plurality of temperature states of the after treatment system (18).
5. The method (60) as claimed in claim 1, wherein the step of measuring the input
signal parameters (32-46) from the exhaust gas, further comprises:
measuring a vehicle performance parameter (40-46) and updating the lookup table (47) to identify abnormality of the soot emission from the engine (12).
6. The method (60) as claimed in claim 5, wherein the vehicle performance parameter (40-46) includes an accelerator pedal position (40), an engine speed (42), an engine torque (44), a vehicle speed (46) and an intake manifold pressure.
7. A control system (10) for detecting and preventing failure modes of a diesel particulate filter (26) placed downstream of an after treatment system (18) arranged in an exhaust passage (19) of an internal combustion engine (12), the control system (10) comprising:
a plurality of sensors (14, 20, 24, 28) connected to the after treatment system (18) to sense a plurality of input signal parameters (32-46) from an exhaust gas of the internal combustion engine (12); and
an after treatment control unit (16) connected to the engine (12) and the after treatment system (18) to receive the input signal parameters (32-46), the after treatment control unit (16) further adapted to:

calibrate a lookup table (47) based on concentration of the input signal parameters (32-46) at a plurality of operating condition of the engine (12) and/or rate of change of the input signal parameters (32-46);
detect abnormality of soot emission from the engine (12) based on deviation of the input signal parameters (32-46) from a predetermined reference value stored on the lookup table (47);
de-rate performance of the engine (12) to prevent failure of the diesel particulate filter (26).
8. The control system (10) as claimed in claim 7, further comprising:
an NOx sensor (14) placed upstream of the after treatment system (18) for measuring an oxygen signal (32) corresponding to an oxygen level in the exhaust gas at the plurality of operating condition of the engine (12) to identify abnormality of the soot emission from the engine (12).
9. The control system (10) as claimed in claim 7, further comprising:
a delta pressure sensor (28) connected in between the diesel particulate filter (26) for measuring an absolute value and/or rate of change of pressure drop (34) across the diesel particulate filter (26) to identify abnormality of the soot emission from the engine (12).
10. The control system (10) as claimed in claim 7, further comprising:
a temperature sensor (20, 24) connected at both ends of the diesel oxidation catalyst (22) for measuring input temperature (36) and difference in temperature (38) across the diesel oxidation catalyst (22) to identify abnormality of the soot emission from the engine (12).
11. The control system (10) as claimed in claim 7, wherein the after treatment
control unit (16) receives vehicle performance parameter (40-46) to identify
abnormality of soot emission from the engine (12).

12. The control system (10) as claimed in claim 11, wherein the vehicle performance parameter (40-46) includes an accelerator pedal position (40), an engine speed (42), an engine torque (44), a vehicle speed (46) and an intake manifold pressure.